Thin film transistor liquid crystal displays (TFT-LCDs for short) have the characteristics of small size, low power consumption, no radiation and so on, have been developed rapidly in recent years, and are dominant in the current flat panel display market. The major structure of a TFT-LCD is a liquid crystal display panel, the liquid crystal display panel includes an assembled thin film transistor array substrate and color film substrate, and liquid crystal molecules are filled between the array substrate and the color film substrate. The liquid crystal display panel achieves grayscale display by controlling the voltages of a display electrode and a common electrode to form an electric field that drives the deflection of liquid crystal molecules. Therein, the liquid crystal molecules need to be driven by an alternating current, and a DC voltage being applied to the liquid crystal molecules for a long time will affect the electrochemical characteristics of the liquid crystal molecules, resulting in a decrease in the lifespan of the liquid crystal display panel. Therefore, the driving voltage must be periodically reversed, that is, divided into positive polarity driving and negative polarity driving. Therein, the positive polarity driving refers to controlling the voltage of the display electrode to be higher than that of the common electrode. The negative polarity driving refers to controlling the voltage of the display electrode to be lower than that of the common electrode. For a liquid crystal molecule, whether positive polarity driving or negative polarity driving, the displayed gray level is the same, as long as the absolute value of its voltage difference is identical.
Therefore, when the absolute value of voltage difference is different under two driving voltages, the gray level displayed by the liquid crystal display panel will be different and make the display screen flicker.